The invention relates to a conveyor mat comprising number of plastic modules succeeding each other in a conveying direction and whose top sides form a conveying face, said modules each being provided, in a transverse direction thereof, with a number of hinge loops which have equal basic forms and which alternately extend forwards and rearwards relative to the conveying direction and converge from a base to a top, said hinge loops being provided, adjacent the top thereof, with slotted holes, said modules each being further provided with a number of interspaces formed to be at least partially complementary to the hinge loops and at least partially bounded by the sidewalls of two hinge loops extending in the same direction, the successive modules of said conveyor mat being coupled by means of hinge pins extending through the slotted holes, such that the forwardly extending hinge loops of the rearmost module can slide between the rearwardly extending hinge loops of the next module between a slit-out position in which the hinge pins abuts against a top-proximal wall of the slotted hole and a slid-in position.
It is observed that whenever the conveying direction is mentioned in this context, the direction is meant in which a particular module can travel along a conveying path. It is further observed that the module can move along the conveying path in two opposite conveying directions and that, accordingly, the terms xe2x80x98forwardsxe2x80x99 and xe2x80x98rearwardsxe2x80x99 depend on the conveying direction chosen.
Such conveyor mat is known from practice and is referred to as xe2x80x98bend matxe2x80x99. By sliding the hinge loops in and out, the conveying path followed by the modules of the conveyor mat can make a bend in the conveying plane, such as a bend in the conveying track.
For assembling a conveyor mat, a smallest possible minimal radius R of a bend lying in the conveying plane is
aimed at. For a conveyor mat of a given width, the minimal radius R is less according as the hinge loops can slide relative to each other through a larger distance. The distance through which the hinge loops can slide relative to each other may be larger according as the pitch of the modules in conveying direction is chosen to be greater, i.e. according as the modules in conveying direction are of longer design. However, in view of the conveyor mat deforming into a polygon, a greater pitch increases the minimal radius R of a bend that can be made by the conveyor mat in a plane perpendicular to the conveying plane and extending in conveying direction. Such a bend is made when the mat travels around a return wheel at an end face of a conveyor mat extending along an endless path. Preferably, the radius R is as small as possible, to enable the end face of such endless conveyor mat to be placed as close as possible against a following conveying member.
The above conditions have together resulted in a band mat of the type as set forth in the preamble, wherein a maximal slide-in distance is realized at a minimal pitch.
A drawback of the known conveyor mat is that the successive modules in their slid-out position can slide relative modules in their slid-out position can slide relative to each other transversely to the conveying direction. This involves the chance of the conveyor mat sliding away transversely to the conveying path and/or the longitudinal axes of a number of modules not being perpendicular to the conveying direction. This may cause increased wear of and damage to the conveyor mat. Moreover, the conveyor mat may become damaged when the hinge pins, during travel around a return wheel, do not extend transversely to the conveying direction.
In addition, WO-A 95/28343 discloses a xe2x80x9cbendxe2x80x9d or xe2x80x9cradiusxe2x80x9d type conveyor mat according the preamble of claim 1, having a projection/recess assembly for blocking lateral movement of the modules in slid-out position. In particular, the forwardly extending hinge loops are provided, between the base thereof and the top-proximal wall of the slotted hole, with a projection in the form of an alignment tab which, in the slid-out position, cooperates with the top of the adjacent, rearwardly extending hinge loop. The side wall of the adjacent hinge loop is provided with a recess, formed as a slot, in which the alignment tab is received during sliding into the slid-in position.
WO-A 91/01261 describes a xe2x80x9cbendxe2x80x9d or xe2x80x9cradiusxe2x80x9d type conveyor mat having the basic lay out of the mat disclosed in WO-A 95/28343. In slid-out position, however, the protrusions of the blocking mechanism cooperate with additional protrusions located near the tops of the rearwardly extending hinge loops.
A problem associated with the alignment tab/slot assembly of WO-A 95/28343 or WO-A 91/01261 is that, when the conveying face is to travel through a bend perpendicular to the conveying plane, e.g. when the mat is to travel around a return wheel, the modules must be in the slid-out position. When travelling through such a perpendicular bend in the slid-in position, the guide tab extends into the slot and will block bending out of the plane of travel. This may lead to breakage of the guide tab or damage to the material surrounding the slot.
Starting from WO-A 95/28343, the objective technical problem is to provide a projection/recess assembly for blocking lateral movement of the modules in the slid-out position, which allows the modules to bend out of the plane of travel when they are in or near the slid-in position.
The object of the invention is to provide a conveyor mat wherein the above drawbacks are avoided while the advantages are retained.
To that end, the conveyor mat according to the invention is characterized by the feature of claim 1.
At least one sidewall of at least one forwardly extending hinge loop is provided, between the base thereof and the top-proximal wall of the slotted hole, with a projection which in said slid-out position cooperates with the top of the adjacent, rearwardly extending hinge loop, and that the sidewall of the adjacent hinge loop is provided with a recess in which the projection can be received during sliding into the slid-in position.
The effect thus achieved is that in said slid-out position, the projection, through cooperation with the top, considerably impedes displacement in transverse direction, while a maximal slide-in direction is maintained.
By constructing the hinge loops at the location of the recesses in the side walls and the projections free of overlapping parts in at least the slid-in position, it is possible for conveyor mat to travel through a bend perpendicular to the conveying plane in or near the slid-in position, without the risk of damage occurring to the projections of the recesses.
The projection and the corresponding recess in the sidewall of successive modules are designed so that between the projection and the sidewall, in a direction substantially transverse to the conveying plane, sufficient space of movement is present for enabling the successive modules to move, from slid-in position and from the conveying face, through a bend in a plane transverse to the conveying face and extending in conveying direction, without damage being caused to the projection and/or the sidewall adjacent the recess. It is thus provided that the occurrence of damage can be avoided when successive modules, when they travel around a divert wheel from the conveying face, are not in the slid-out position, for instance due to the fact that the longitudinal axes of the successive modules do not extend entirely parallel, or that the successive modules are stuck or clamped in slid-in position.
The projection and the sidewall at the location of the recess, viewed in a direction transverse to the conveying face, are free of any overlapping parts and/or the projection and the sidewall at the location of the recess lie substantially next to each other. It is thus provided that in a simple manner, a relative movement in two directions transverse to the conveying face is enabled and that the chance of fouling of the projection and/or the recess is reduced. In particular the recess is formed by one or more guide faces extending substantially transversely to the conveying face, from the bottom side to the top side of the hinge loop.
In a next embodiment, both sidewalls of a forwardly extending hinge loop are provided with a projection between the base and the top-proximal wall of the slotted hole, and the sidewalls of the opposite, rearwardly extending hinge loops are each provided, adjacent the top thereof, with a corresponding recess.
Accordingly, in said slid-out position, displacement in transverse direction is further obstructed.
In another embodiment, the conveyor mat according to the invention is characterized in that the hinge loops located in a part located adjacent a lateral side of the conveyor mat comprise substantially flat sidewalls. It is thus provided that the minimal section of the hinge loops which, when traveling around a bend in the horizontal plane, are subjected to a heavier load, is greater, while the hinge loops located more at the center the conveyor mat and which are subjected to a less heavy load, obstruct the displacement in transverse direction.
In again another embodiment, the conveyor mat according to the invention is characterized in that the hinge loops bounding a lateral side of the conveyor mat have, in transverse direction of the module, a greater width than the other hinge loops. It is thus provided that the tolerance of the length of the hinge pins can chosen to be greater.
In yet another embodiment, the conveyor mat according to the invention is characterized in that at least a part of the hinge loops bounding a lateral side of the conveyor mat are provided, adjacent their top, with a recess that extends substantially transversely to the conveying direction and that intersects the slotted hole. It can thus be provided that in the recess, a locking member can be received for retaining the hinge pin that is inserted from the conveying face.
The locking member can be elegantly provided with preferably spring-loaded, laterally extending parts which, in mounted condition, can extend into the slotted hole. Further, the locking member may comprise an edge which, in mounted condition of the locking member, is accessible from the lateral side of the conveyor mat via the slotted hole. In this manner, the locking member can readily be removed from the recess by means of a screwdriver. It is observed that the locking member can also be advantageously applied to other types of modular conveyor mats.
In a following embodiment, the conveyor mat according to the invention is characterized in that a number of modules are each provided, at the bottom side thereof, with an outwardly extending guide member for cooperation with a guide mounted on a conveying path, which guide member has a lateral side thereof provided with a face beveled transversely to the conveying direction. In this manner, displacement in transverse direction is further obstructed, while at the same time, the conveyor mat is prevented from rising when traveling through a bend in the conveying plane.
Further, the face of the guide members that is foremost and/or rearmost in conveying direction is preferably provided with a bevel extending in rearward or forward direction respectively. It is thus provided that the guide members can project sufficiently far outwards without increasing the minimal radius R of a bend that can be made by the conveyor mat in a plane perpendicular to the conveying face the extending in conveying direction. It is observed that such guide members can also be advantageously applied to other types of modular conveyor mats.
Further elaborations of advantageous embodiments of the conveyor mat according to the invention are described in the subclaims.